It’s fire season again! The warm glow of a fire is one of the finest comforts of the colder months. To keep everything in working order, it’s good to become familiar with all the parts and workings of your home’s fireplace.
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The hearth is oft mentioned in literature’s scenes of “hearth and home.” The word itself evokes a warm feeling. But “hearth” is also the technical term for the floor of the fireplace. The inner hearth is the bottom of the firebox and is made of firebricks, a special heat-resistant brick that lines the firebox. The hearth extension, or hearth pad, can be flush or raised and it constructed from a noncombustible material.
The firebox is where the fire burns and the smoke rises up the chimney. Firebox isn’t a term homeowners use often because they normally refer to the firebox, the hearth and the surround as a “fireplace.”
The surround is the exterior of the fireplace. It serves to protect the combustible walls around the fireplace and be made of wood, stone, steel, brick or concrete. The surround is typically decorative. The mantle, an extension added to the surround, is used for decor like pictures and other accessories.
Situated above the firebox and extending the length of the chimney, the flue is the open passage that allows smoke and gases to travel up the chimney. The “throat” of the flue is the opening right above the firebox.
The chimney holds the flue. It usually projects several feet above the roof of the house.
The spark arrestor is a screen that is fitted on top of the flue to help prevent lit embers from escaping the chimney. Modern spark arrestors are part of chimney caps.
A chimney cap covers the chimney. It is like a little roof that spans the flue opening at the top of the chimney. It is usually made of steel or copper. It helps keep leaves, snow and rain from entering the chimney and discourages animals from taking up residence there. Modern chimney caps usually act as spark arrestors too.
The damper is a heavy-duty flap that opens and closes by hand. It is above the firebox in the chimney and is used to manage the flow of hot and cold air when the chimney is not in use. Dampers must remain open for the full duration of the fire so smoke can travel up the chimney. Dampers can be closed when the fireplace is not in use to prevent ambient heat from the house from escaping or to keep cold outdoor air from getting into the house.
A chimney damper, also called a top-down damper, sits on the top of the chimney. It is a damper operated by a cable. Its purpose is to help stop cold downdrafts from chilling the chimney and its walls. Chimney dampers are not installed on all chimneys.
Some fireplaces have heavy glass or metal doors that are installed with the masonry of the fireplace (often supported by the lintel). The doors cut off the flow of air to the firebox. They are closed when the fireplace is not in use and opened when it is.
The smoke chamber is a small area above the throat of the flue. A notch in the chimney, called a smoke shelf, acts as a support for any flue liner that may be installed in the chimney. The smoke chamber is usually wide at the bottom and narrows to the flue’s size. The purpose of the chamber is to smoothly draw the smoke out of the firebox and into the flue. This place in the chimney is often overlooked, even by professionals. Remind any maintenance pros to clean and inspect the smoke chamber.
A few fireplaces have a trap door under the firebrick on the inner hearth, aka the floor of the firebox. It serves to collect the ash in a smaller space below for more convenient clean-up.
Fireplaces are wonderful home features but must be maintained and treated with care. Knowing the parts of the fireplace will help you communicate with professionals effectively. Set up a schedule of yearly maintenance and you’ll have many cozy nights ahead.